1. Field of the Invention
The present invention relates generally to a switch wire-connection terminal block structure, and more particularly to an improved locking structure of a terminal block for locking wire terminal. In the condition that the volume of the terminal block is not increased, the terminal block has a full gap between the locking member and the locking hole. Therefore, the terminal block is applicable to closed wire terminals to facilitate the connection between wires.
2. Description of the Related Art
A switch wire-connection terminal block is a power switch member with contact terminals. The switch wire-connection terminal block is applied to circuit system in electronic and electrical engineering field. The switch wire-connection terminal block is mainly mounted on inner face of the operation panel or distribution box panel of electronic and electrical equipment to connect the wiring circuits thereof. The switch wire-connection terminal block has a pushbutton protruding from the surface of the operation panel or distribution box panel. The switch wire-connection terminal block can be further connected to the switch wire-connection terminal block of other wiring circuits in the electronic and electrical equipment for an operator to press the pushbutton so as to operate and control powering on/off of the respective wiring circuits. Accordingly, the switch wire-connection terminal block is used to power on/off the circuits.
Please refer to FIG. 1, which is a sectional view of a conventional switch wire-connection terminal block. The conventional switch wire-connection terminal block has a casing 1a and a pushbutton 2a movably disposed at front end of the casing 1a. The pushbutton 2a extends into the casing 1a to bear the elastic force of a spring 21a. A first contact terminal 41a and a second contact terminal 42a are disposed in the casing 1a on two sides of the pushbutton 2a. An electro-conductive member 3a is also disposed in the casing 1a and positioned between the first and second contact terminals 41a, 42a. The electro-conductive member 3a is connected with the pushbutton 2a. Two ends of the first and second contact terminals 41a, 42a are respectively formed with a locking hole 411a, 421a and a contact section 412a, 422a corresponding to the electro-conductive member 3a. By means of pressing the pushbutton 2a, the electro-conductive member 3a is driven by the pushbutton 2a to contact or separate from the contact sections 412a, 422a of the first and second contact terminals 41a, 42a so as to power on or power off the first and second contact terminals 41a, 42a. 
In addition, the rear end of the casing 1a is formed with two receiving holes 15a, 16a respectively in communication with the locking holes 411a, 421a of the first and second contact terminals 41a, 42a. Two lateral ends of the casing 1a are further respectively formed with two wire sockets 17a, 18a. The wire sockets 17a, 18a respectively intersect and communicate with the receiving holes 15a, 16a. Moreover, a screw 51a, 52a is disposed in each receiving hole 15a, 16a for locking into the locking hole 411a, 421a. In use, the screws 51a, 52a are first framed by external wire terminals and then the screws 51a, 52a are locked into the locking holes 411a, 421a of the first and second contact terminals 41a, 42a to electrically connect with the first and second contact terminals 41a, 42a. 
However, in order to commonly frame the screws 51a, 52a with various external wire terminals 91a, 92a (including open and closed wire terminals), a full gap H must be reserved between the tail ends of the screws 51a, 52a and the locking holes 411a, 421a in an unlocked state. Only in this case, various external wire terminals 91a, 92a, including closed wire terminals can extend into the casing 1a to frame the screws 51a, 52a. 
As aforesaid, the receiving holes 15a, 16a intersect and communicate with the wire sockets 17a, 18a. Therefore, after the screws 51, 52a are unscrewed and loosened from the locking holes 411a, 421a, the screws 51a, 52a tend to tilt down toward the wire sockets 17a, 18a. Under such circumstance, the locking ends of the screws 51a, 52a are displaced from the positions in alignment with the locking holes 411a, 421a. As a result, when it is desired to screw the screws 51a, 52a back into the locking holes 411a, 421a, it is hard to aim the screws 51a, 52a at the locking holes 411a, 421a and screw the screws 51a, 52a into the locking holes 411a, 421a. This is quite troublesome to an operator.
To solve the above problem, an improved switch wire-connection terminal block employs a design of a correction gasket member 61a, 62a, which is fitted on each of the screw 51a, 52a. In general, a guide channel 151a, 161a is formed on a lateral side of the receiving hole 15a, 16a in communication therewith. The guide channel 151a, 161a extends in a direction to the locking hole 411a, 421a. In addition, the gasket member 61a, 62a has a guide bar 611a, 621a extending from the edge of the gasket member 61a, 62a toward the locking hole 411a, 421a. The guide bar 611a, 621a is slidably disposed in the guide channel 151a, 161a. Accordingly, the guide channel 151a, 161a can guide the guide bar 611a, 621a of the gasket member 61a, 62a fitted on the screw 51a, 52a to aim the screws 51a, 52a at the locking hole 411a, 421a. However, such design has a shortcoming that the guide channel 151a, 161a and the guide bar 611a, 621a both extend in the direction to the electro-conductive member 3a and the contact sections 412a, 422a of the first and second contact terminals 41a, 42a. The guide channel 151a, 161a and the guide bar 611a, 621a are so close to the electro-conductive member 3a and the contact sections 412a, 422a of the first and second contact terminals 41a, 42a that the guide bar 611a, 621a tends to interfere with the electro-conductive member 3a and the contact sections 412a, 422a of the first and second contact terminals 41a, 42a. For avoiding the interference, it is necessary to increase the height of the casing 1a. This leads to increase of the volume of the casing 1a and is not beneficial to miniaturization of the casing 1a. 
Furthermore, after the screws 51a, 52a are unscrewed from the locking holes 411a, 421a, the screws 51a, 52a are possibly not detached from the locking holes 411a, 421a. Especially when the pushbutton 2a of the casing 1a is directed downward and the receiving holes 15a, 16a are open to upper side, the screws 51a, 52a can be hardly moved away from the locking holes 411a, 421a under affection of gravity. Under such circumstance, the tail ends of the screws 51a, 52a cannot be spaced from the corresponding locking holes 411a, 421a to keep the gap H. As a result, the closed wire terminals 91a, 92a cannot extend between the screws 51a, 52a and the first and second contact terminals 41a, 42a. To solve this problem, a further improved switch wire-connection terminal block employs a spring to drive the screws 51a, 52a to normally move away from the locking holes 411a, 421a when unscrewed. For example, a spring 70a is disposed in the guide channel 151a to drive the guide bar 611a and the gasket member 61a to move the screw 51a in a direction away from the locking hole 411a. However, such design still has a shortcoming that in order to avoid interference between the guide channel 151a, the spring 70a and the guide bar 611a and the electro-conductive member 3a and the contact sections 412a, 422a of the first and second contact terminals 41a, 42a, it is also necessary to increase the volume of the casing 1a. This is not beneficial to miniaturization of the casing 1a. 